Stanford Arizona garden - Opuntia

Here is an Opuntia composition, from my last visit to Stanford cactus garden. Late light of the fall day  gives the pad this both gentle and crisp touch, making photographer's job easy. This is a tall large-padded Opuntia, I have to look up it's name some day.

Notocactus ottonis vencluianus

Notocactus (Parodia) ottonis 'vencluianus' is considered a flower color variation of common yellow-flowering species. The plant stem does look a lot like that of N.ottonis, but I've not heard of successful crossing of these plants. Than may indicate that this is actually a different species all together, another example of converging evolution in Cactaceae.
The flower color is somewhat too bright and almost hurting to look. It is somewhat unclear to me why this form is not seen more often in collections, as growing it not any different than growing any other Notocactus, and seeds are readily available from many good sources.

Pediocactus simpsonii

Pediocactus simpsoni is a widely spread species, occurring through USA areas from Rocky Mountains and west. It is adopted for the environment where one would not expect to see cactus - areas with permanent winter snow cover, where pine trees not yuccas grow.
The plant is pretty easy in culture, once it's requirements understood. Pedoicactus simpsonii gets most of it's year's water supply from snow melt. It blooms on southern slopes at the time when nearby north facing sides of the same hill are still under snow, and air is cool.

Grusonia clavata

Genus Grusonia was created  for small North American Opuntoides that distinguish from Cylindropuntias by lack of papery spin cover - 'sheath'. They are low spreading plants, often forming mats, and easily noted for downward pointing spines. Grusonia clavata is more often than other species seen in collections, for it's compact growth and dagger-like spines.
Grusonia buds are also easily recognized for they shape with distinct long 'tube'. The plant in picture had only two mature segments a that time, and was ready to flower at the size.

Echinocereus sciurus floresii

The closeup of A typical Echinocereus flower - green stigma, bright petals. Flowers ate large and wide open, making pollination easy, either natural or artificial - with a brash.All Echinocerei are self sterile and require second plant and cross-pollination o develop seeds. 

Mammillaria vetula 'gracilis"

M. gracilis is very common plant in Europe, often the first cactus in collection. It is offsetting freely, and readily roots. When grown under plenty of light this plant forms very attractive dense white clumps, with stubby black central spines. Fruits are rarely seen, and are green in color.

Mammillaria pertophila

Mammillaria pertophila is Baja California species, from the Southern tip of peninsula. It is a small in nature, clumping in culture plant noted for its dense wool and greenish flowers. Larger plants look nice with lots of white wool in axiles. 

This species is pretty easy in culture, but not that commonly seen, usually only in specialized collections.

Mammillaria elongata 'echinaria'

This picture  of young seedlings if asked for plant IF will puzzle almost every cactus collector. Mammillaria elongata is one of the most common cacti in culture, but 'echinaria' form is not so well known. This plant was originally described as M. echinaria, but the only notable difference with M. elongata is the persistent central spines, so taxonomically M. echinaria was downgraded to a merely form.
That does not change that it is very decorative plant, one of the most attractive in the genus.

Mammillaria crucigera

First description of this unusual Mammillaria was published in 1832, almost 180 years ago. Despite that, it is still uncommon and desirable plant among collectors. The plant's stem is tightly covered with short spines, and with age white cotton develops from axiles. Pink flowers are tiny.
The plant is slow to develop and somewhat rot pron when young, may be due to grower's lack of patience. Large plants usually present no problems when grown in well aerated pure mineral substrate/

Acanthocalycium spiniflorum 'violacium'

This nice plant from Argentina is a long time favorite among collectors. Easy in culture and ready blooming plant, it produces it's pink flowers reliably over the summer.
There are multiple forms of this species available from commercial seed sellers, with both pink and white flowers and varying spines.

Gymnocalycium spegazzinii

This cactus - Gymnocalycium spegazzinii - is known pore for it's spines than flowers. It's downward looking spines resemble claws, and when plant shivered during drought period they create tight cower over the stem.

Echinocereus subinermis

Echinocereus subinermis is a common in culture plant, native to Sonora state. With low ribs and short spines it can easily be mistaken for Echinopsis when not in flower - the overall plant look is very similar. Flowers of cause will reveal the true identity.
This species flowers yellow, not the most common color among Echinocerei. Flowers are produced reasonably easy.

Gymnocalycium ragonesei

Gymnocalycium ragonesei is naive to salty plains of San Juan, Argentina. This is a species of dry areas, may be the driest of all Gymnocalyciom inhabited lands. It is a slow growing plant with brown stem, and often flat as pancake. In culture it eventually branches, and small clumps are often producing little shows of white blooms.

Parodia lauii

Parodia lauii - one of the relatively resent additions to old genus Parodia. Parodias used to be very popular among growers, and for good reason - they are very colorful plants, with nice flowers too. In recent years  popularity of the genus subsided significantly, the genus simply going out of fashion I'd say. It is really hard to find a good specialized Parodia collection now days.
But plants are same pretty, and with South America's wild places becoming more accessible lots of nice new forms are available in trade. Don't turn away from those beauties!

Cylindropuntia ramoissima flower bud - 'cactella'

Cactus flower is not a true flower, but a meta-morphed sprout, or stem. It is very clearly seen on C. ramoissima example. At early stage of development new flower and new stem are very hard to tell apart, and it is likely they are not different at first, with sprout turning to bud in response to some plant hormones. In my observation, in the greenhouse culture C. ramoissima produces flowers only when in spring time, after the new growth has started, I stop watering plants. That might be an adaptation to grow as much stems as water supply permits this year, and produce flowers once rains has stopped.
The special botanical term 'cactella' was coined to signify this specific feature of flowers in Cactus family. That is, A.Doweld introduced this term as a name for this cactus-specific stem-flower and stem-fruit organ.

Cumulopuntia boliviana

Cumulopuntia boliviana is a plant from high-altitude deserts of Bolivia and Argentina. It forms large clumps in the wild, but in culture it is usually seen as a smaller plant - due to it's slow development.
The pictured plant is a form with especially long spines, over 4 inches long and potentially longer. The plant steadily develops two-three new segments each year.

Thelocactus hexaedrophorus

Thelocactos hexaedrophorus is one of those 'classical' plants, well known and still very desired by cactus collectors. This is a slow developing singular plant, with simple grayish stem and large flower. Flowers produced continuously over the summer.

The plant was first described back in 1839, as Echinocactus hexaedrophorus. 

Lobivia haematantha v. jasimanensis

Lobivia haematantha v. jasimanensis WR 792 is one of many nice forms of variable L. haematantha. Plants are small, with noted long back central spine and fleshy roots. Flowers relatively large, and white throat adds color in them.

Ariocarpus agavoides

Smallest of all Ariocarpus, A.agavoides can bloom at only two years old, if grown properly. The small plant stays mostly underground, with thin tubercles protruding above the surface.
Nice pink flowers open in the fall, same as all other Ariocarpus. The distinct feature of this species is that it is the only Ariocarpus that actually has spines.

Coryphantha sulcolanata

Coryphantha sulcolanata is Mexican species, closely related to C.elephantidens but never has pink blooms. Thick round tubercles with plenty of white felt produced at the plant's top make pretty appearance even without flowers. Large silky flowers stay open for two days, like with other coryphanthas.

Notocactus herteri

Notocactus (Parodia) herteri is South American species from Uruguay. It is a larger plant, growing as a ball to a size of 6 inches or more and only after that slowly turning to a column.
Tho plants I have, grown from the same bag of seeds, have much different flower color. The plant at picture has flowers dark pink, and the other produces much lighter pink, almost lavender blooms. Both plants bloom freely and reliably, but only once during the season, in mid-summer.

Weingartia neumanniana

Weingartia neumanniana, is the smaller and slower growing Weingartia, sometimes considered as a difficult to grow plant. The plant has somewhat grayish stem and flowers that are larger than with more common Weingartias, but not that abundant.

This species has thick fleshy roots, the source of problems when not grown in mineral substrate. The common cactus care suits it well, with may be slightly restricted water supply in the summer. Large clumps of this species are rarely seen in culture and always draw a stare.

Matucana paucicostata

Matucana paucicostata is probably the smallest Matucana species. The plants mature ans start blooming at the size of walnut, and generally do not overgrow the mid-sized apple. Large plants usually open flowers in small bouquets of 5-10 blooms at time, forming pretty crown. Looking close at the flower is also a pretty sight, with gentle changing color shades of petals and tight bunch of filaments around style.

Sulcorebutia pulchra

Sulcorebutias are known for their colorful flowers and S.pulchra is a good example of that. It is blooming while small plant, with flowers blood-red like the one pictured.
In culture Sulcorebutias are usually easy, but some species do tend to rot unexpectedly. Porous pure mineral substrate helps as usual.

Chamaelobivia 'Yellow bird'

Another Chamaelovia hybrid - yellow flowers this time. 'Yellow bird' is a bit shy bloomer, but flowers are nice and relatively large. 

Chamaelobivia hybrid 'Fire Chief'

This is old hybrid produces light-red flowers that are larger and lighter in color than with the species. Like all Chamaelobivias it is a free blooming and easy plant, suitable for beginner. Common cactus culture suits it well.

Mammillaria melaleuca

 Mammillaria melaleuca flowers are remarkably similar to M. sphaerica's. It has a very limited range, coming from Mexican state Tamailupas where much more widely distributed M.sphaerica grows as well. These two species are probably closely related. 

 Mammillaria melaleuca is relatively easy to grow plant, the largest one I have is about 10cm across and still singular. It's blooms usually form classical Mammillaria 'crown'.

Rebutia albopectinata

Here is another pic of this plant, one of my favorites. It is a R. heloisa relative with similar looking flowers, but a much larger plant. This clump I have produces flashes of hundred or so flowers couple times a season. 

Rebutia narvaecensis

Rebutia narvaecensis is a relatively recent discovery and a new favorite from that popular genus. The main attraction is of cause it's flowers of unusual light-pink color. 

As most Rebutias this is free-flowering genus that grows best with maximum light but does not like heat. For hot periods I move all Rebutias into shady area of my greenhouse.

Lobivia oligotricha

Lobivia oligotricha is a small plant with flattened stem and red to pink flowers. As most Libivias it is easy to grow and ready flowering plant.

The large variety of Lobivia forms is available nowadays for an interested collector, and the genus makes a good target for specialized collection. Generally easy plants with compact growth and bright flowers - old classic.